The invention relates generally to a method of forming a copper wiring in a semiconductor device, and more particularly to, a method of forming a copper wiring in a semiconductor device capable of not only realizing reappearance (also expressed as reproducibility) of the copper deposition process but also obtaining a copper thin film having a good film quality by establishing a metal organic chemical vapor deposition (MOCVD) process technology in which 1,1,1,5,5,5-hexafluoro-2, 4-pentadionato (3,3-dimethyl-1-butene)-copper(I) (hereinafter called (hfac)Cu(DMB)) compound is used as a copper precursor.
As semiconductor industries move into an ultra large scale integration (ULSI), the geometry of devices reduces to a sub-half-micron region, while the circuit density thereof become increased in view of improved performance and reliability. Due to these reasons, a copper thin film is usually employed as an interconnection material useful in an integration circuit since the melting point of the copper thin film is higher than that of an aluminum thin film in forming a metal wiring in a semiconductor device. The use of copper thin film as interconnection material improves the reliability of a semiconductor device due to its higher resistance against electro-migration (EM) and increases signal transfer speed due to its low resistivity.
In a method of forming copper wiring, the copper deposition process is important in realizing higher device reliability and higher integrated device transfer speeds. Accordingly, various deposition methods are implemented when forming copper wiring, such as physical vapor deposition (PVD), electroplating, electroless-plating, and metal organic chemical vapor deposition (MOCVD). Because the MOCVD deposition method is significantly affected by a copper precursor, there is a need for a process that can easily deposit a copper precursor. Furthermore, a delivery system by which the copper can be safely moved must also be developed.
The MOCVD method of copper deposition may employ several types of liquid delivery systems (hereinafter called LDS), including: an LDS employing a bubbler method; an LDS such as direct liquid injection (hereinafter called DLI); an LDS such as control evaporation mixing (hereinafter called CEM); and an LDS having a vaporizer of an orifice type or a spray type. A compound comprising a copper metal called a precursor in an LDS is degraded to form a copper deposition.
In the copper precursor used in MOCVD, two compounds were developed. These compounds were copper II valence (Cu) compound such as 1,1,1,5,5,5-hexafluoro-2,4-pentadionato-copper(II) and Cu (hfac)2 compound, each having a low vapor pressure. Following the development of these two compounds, another compound, copper I valence (CuI), has been developed. Copper I valence (CuI) has a high deposition speed since it has a higher vapor pressure than the copper II valence compound and allows high quality copper thin film deposition in a low temperature of 150-250xc2x0 C. The 1,1,1,5,5,5-hexafluoro-2,4-pentadionato(trimethylvinylsilane)-copper (I) (hereinafter called (hfac)Cu(TMVS)) compound of the currently-developed various copper I valence compounds is a representative copper precursor for use in MOCVD that has been widely used since it remains at a liquid phase at room temperature and allows a high quality copper thin film at a low temperature. Even with these advantages, however, the (hfac)Cu(TMVS) compound has a problem that it is degraded at room temperature. Thus, the (hfac)Cu(TMVS) compound has difficulty in reappearance when applied to the process of manufacturing a semiconductor device. Accordingly, although the (hfac)Cu(TMVS) compound has an advantage over the several developed precursors because of its vapor pressure characteristics, it has problems in securing reappearance in the conventional LDS. As such, the (hfac)Cu(TMVS) compound will have great difficulty in securing reappearance unless a new LDS that can safely carry copper precursor is developed. Further, because the range between the vaporization temperature and the condensation temperature in the (hfac)Cu(TMVS) compound is extremely narrow, there is a problem of maintaining the temperature constant. Also, the (hfac)Cu(TMVS) compound can only be safely used for about one year if it is used with a stabilizer.
In order to solve the problems with in the (hfac)Cu(TMVS) compound, a (hfac)Cu(DMB) compound has been developed as a precursor. The (hfac)Cu(DMB) compound is a new compound that is developed using 3,3-dimethyl-1-butene (hereinafter called DMB) as Lewis base ligand. DMB used in this compound has a low molecular weight and high vapor pressure. Because the (hfac)Cu(DMB) compound uses DMB instead of a methyl group of VTMS as a Lewis base ligand, the compound has a higher in a vapor pressure than the (hfac)Cu(TMVS). Therefore, the (hfac)Cu(DMB) compound is a good precursor since it can significantly improve poor deposition speed, which is one of the biggest problems in a MOCVD Cu precursor. However, because MOCVD process technology that employs a (hfac)Cu(DMB) precursor in a conventional LDS has not been established, the (hfac)Cu(DMB) compound has not been commercialized.
It is therefore an object of the present invention to provide a method of forming a copper wiring in a semiconductor device capable of not only realizing reappearance of copper deposition process without developing a new LDS but also obtaining a copper thin film having a good film quality deposition process. This is performed by optimally setting the conditions of a copper deposition apparatus to establish a MOCVD process technology in which a (hfac)Cu(DMB) compound is used as a precursor.
In order to accomplish the above object, a method of forming a copper wiring in a semiconductor device according to the present invention is characterized in that it comprises the steps of: forming an interlayer insulating film on a semiconductor substrate in which various components for forming a semiconductor device are formed; forming a contact hole and a trench on said interlayer insulating film; forming a diffusion barrier layer on the surface of said interlayer insulating film including said contact hole and said trench; depositing in-situ a Cu seed layer on the surface of said contact hole and said trench on which said diffusion barrier layer is deposited using a (hfac)Cu(DMB) precursor by metal organic chemical vapor deposition (MOCVD) method; plating Cu so that said contact hole and said trench on which said Cu seed layer can be sufficiently filled using a plating method; and performing a chemical mechanical polishing to form a Cu wiring.
Also a method of forming a copper wiring in a semiconductor device according to the present invention is characterized in that it comprises the steps of: forming an interlayer insulating film on a semiconductor substrate in which various components for forming a semiconductor device are formed; forming a contact hole and a trench on said interlayer insulating film and then forming a diffusion barrier layer on the surface of said interlayer insulating film including said contact hole and said trench; depositing in-situ a first Cu seed layer on the surface of said contact hole and said trench on which said diffusion barrier layer is deposited by a physical vapor deposition method; depositing a second Cu seed layer on the surface of said contact hole and said trench on which said first Cu seed layer is deposited, using a (hfac)Cu(DMB) precursor by metal organic chemical vapor deposition method; plating Cu so that said contact hole and said trench on which said first and second Cu seed layers are stacked can be sufficiently filled, by a plating method; and performing a chemical mechanical polishing process to form a copper wiring.
The copper seed layer deposited using the (hfac)Cu(DMB) precursor by a MOCVD method uses a copper deposition apparatus comprising a reactive chamber and a liquid delivery system. The liquid delivery system includes a bubbler, a direct liquid injection system, a control evaporation mixer, a system having a vaporizer of an orifice type, and a system having a vaporizer of a spray type.
The deposition conditions of the copper seed layer includes maintaining the temperature of a means for vaporizing a (hfac)Cu(DMB) precursor in a liquid delivery system, for example a canister of a bubbler, a vaporizer of a direct liquid injection, a control valve of a vaporizer in a control evaporation mixer and a vaporizer of an orifice type or a spray type, to be in the range of 20-120xc2x0 C. Also, the deposition conditions of the copper seed layer keeps the temperature of gas lines and source lines from the liquid delivery system to the reactive chamber, the internal temperature of the reactive chamber and the temperature of the showering head in the reactive chamber to be the same as the temperature for vaporizing the (hfac)Cu(DMB) precursor.
In addition, the deposition conditions of the copper seed layer are as follows: the temperature of the susceptor plate in the reactive chamber is in the range of 120-280xc2x0 C., the internal pressure of the reactive chamber is in the range of 0.1-5 torr, the distance between the showering head and the susceptor plate in the reactive chamber is in the range of 1-50 mm and the flow ratio of the (hfac)Cu(DMB) precursor is in the range of 0.1-1.0 sccm.